My wife and I were traveling on US HWY 51 North in the Portage area (we had just filled up at the Portage Quick Trip), when, just above the trees, we noticed several bright lights that looked almost the color and size of streetlights. They would wink on like someone powering up a 12 volt bulb with a 6 volt battery (kind of slow to intensity). At first we thought we were seeing the blinking of a tower through the trees so we didn't pay them too much attention. But then we saw them again, after our line of sight cleared the trees, we realized the lights were not from a tower. Our next thought was landing lights from several planes because we noticed there was an abnormal amount of planes flying in the area. That struck us as odd if it were true because why would aircraft fly so close to one another and why would they flash the landing lights (not the green and red clearance lights on the wings). Plus, they would have to all be facing us pretty much exactly the same direction for them to all be the same intensity, there were about 7- or 8 of them in a somewhat straight line four or so on top and perhaps three or four below spaced perhaps a finger width apart from one another (it was hard to tell if there was a pattern because we were in the car going 65- 70 mph). As we drove on for about 6 to 8 miles we saw them again in approximately the same position as before which told us one of two things, either the lights were moving our same direction, or they were much higher up then they appeared. We saw them several times again sometimes by themselves sometimes in a group, so we thought we could possibly photograph them with our digital camera (they were occurring very often). We pulled off the Hwy in a rest stop and got out of the car and counted about 5 airplanes circling in the area. We then realized the planes were not civilian, they were way too fast and flying very tight maneuvers, plus they would all come very close to one another at all different directions and when they converged that's when we would see the lights flash, we then realized the lights were not the planes, but the planes (we now could hear them) were converging on whatever was making the lights. We tried to get a picture of the lights but with the almost full moon and the streetlights in the wayside we couldn't. There was a white minivan in the parking lot in front of us watching the lights as well. After about 35 minutes or so we didn't see them anymore and the jets eventually flew away (in a small formation) so we left too.